Genealogy sites have helped solve major crimes. Police in Nancy Guthrie's case might turn to them

Authorities trying to solve the disappearance of Nancy Guthrie say they might tap DNA genealogy databases, the same step that police took to unravel a decades-old series of murders in California and the fatal stabbings of four college students in Idaho.

The strategy could be fruitful: If unidentified DNA evidence can be connected to someone — even a distant relative — in a common genealogy database, it would give investigators more information and possibly lead to a suspect in Guthrie's kidnapping in Arizona.

''It's a fantastic tool,'' said Ruth Ballard, a geneticist in California who specializes in DNA and has testified in hundreds of court cases. ''If it's a good quality sample and they're able to get a profile, they could find a hit on that fairly quickly.''

The sheriff's department in Pima County, Arizona, said DNA collected so far in the investigation has not turned up any matches in a national criminal justice database known as CODIS, which has DNA profiles from convicted criminals and, in some states, people arrested for certain crimes.

''Investigators are currently looking into additional investigative genetic genealogy options for DNA evidence to check for matches. CODIS is one option of many databases that are available,'' the sheriff's department said Tuesday.

The department said Wednesday that biological evidence from Guthrie's Tucson-area home was being examined and that DNA profiles were at a lab for analysis.

Guthrie, the mother of NBC ''Today'' co-anchor Savannah Guthrie, has been missing from her home since Feb. 1. The FBI said gloves found about 2 miles (3.2 kilometers) away appeared to match those worn by a masked suspect who was recorded on a porch camera.

GEDmatch has been credited with helping solve the case of the so-called Golden State Killer. Police used DNA from crime scenes to find a distant relative and build a family tree that led to Joseph DeAngelo Jr. In 2020, he pleaded guilty to 13 killings and dozens of rapes in California in the 1970s and '80s. He is serving life in prison without possibility of parole.

Barbara Rae-Venter, an expert genealogist who worked on the DeAngelo case, said patience often is needed in high-tech sleuthing.

''I've solved cases in less than eight hours where people shared a lot of DNA with the suspect. Other cases, you're still working on them two years later. This could take awhile,'' Rae-Venter told CNN, referring to the Guthrie effort.

In Idaho, DNA from a knife sheath helped point to Bryan Kohberger in the killings of four University of Idaho students in 2022. Investigators used genealogy sites to build a family tree and pulled trash from the Pennsylvania home of Kohberger's parents to make a connection. Kohberger pleaded guilty and was sentenced to life in prison.

Ballard said the source and quality of the DNA evidence held by police can be factors when trying to find matches on genealogy sites.

And there can be other hurdles.